Indomethacin loaded chitosan microspheres. Correlation between the erosion process and release kinetics

Area of Science:

• Biomaterials Science
• Pharmaceutical Sciences
• Drug Delivery Systems

Background:

• Chitosan microspheres are promising drug delivery vehicles.
• Controlling drug release from microspheres is crucial for therapeutic efficacy.
• Citric acid modification and indomethacin loading present a novel formulation.

Purpose of the Study:

• To synthesize and characterize chitosan microspheres covalently linked with citric acid and loaded with indomethacin.
• To investigate the influence of chitosan concentration and pH on indomethacin release kinetics.
• To analyze the impact of these parameters on drug diffusion and solubility within the eroding matrix.

Main Methods:

• Preparation of chitosan microspheres via covalent linkage with citric acid.
• Loading of indomethacin into the prepared microspheres.
• In vitro release studies under varying chitosan concentrations and pH conditions (e.g., pH 7.4).
• Analysis of release kinetics, including deviations from Fickian models.

Main Results:

• Chitosan concentration and pH significantly affected indomethacin release kinetics.
• Higher chitosan concentrations and pH 7.4 led to deviations from Fickian release towards zero-order kinetics.
• These variations were attributed to changes in drug diffusion and solubility within the eroding chitosan matrix.

Conclusions:

• Chitosan concentration and release medium pH are critical parameters for controlling indomethacin release from citric acid-modified microspheres.
• The observed shift to zero-order kinetics at higher chitosan concentrations and neutral pH suggests potential for sustained drug delivery.
• Understanding these release mechanisms is vital for optimizing chitosan-based drug delivery systems.